As with any programming language, the first thing you should learn is how to write the most basic of text onto the screen.
PHP isn't an exception to this. Here is the simple code necessary to write 'Hello world!' on a page.
PHP Code:
<html>
<head>
<title>Hello world example</title>
</head>
<body>
<?php echo '<p>Hello world!</p>'; ?>
</body>
</html>
Of course, the above code is for a full page of HTML. At the absolute basics, you could use this:
PHP Code:
<?php echo '<p>Hello world!</p>'; ?>